1. Field of the Invention
The present invention is a high efficiency, high energy slurry mixer used primarily to mix oil field cement in a recirculating system for cementing the casing in oil and gas wells and method for mixing. The cement mixer mixes dry powder with water and recirculated slurry to create the cement mixture. The cement mixer employs a straight through design that is easier to clean than previous designs and which can be seen straight through when the connection at the dry powder inlet is removed from the mixer. The cement mixer also has increased number and volume of annular water flow openings and recirculation openings which allows for more water and slurry flow with less erosion to the mixer surface than previous designs. The previous design did not allow for more recirculation and water jets because there was not room to add them. The new design allows the mixer surfaces to be manufactured with less expensive materials without sacrificing performance and life, thereby reducing the cost of the equipment. The present design eliminates most of the wear problems experienced in earlier designs resulting in the equipment lasting longer before repair or replacement is required.
2. Description of the Related Art
The discussion regarding related art appearing in U.S. Pat. No. 6,749,330 is hereby included by reference. The cement mixer design taught in U.S. Pat. No. 6,749,330 had several problems. First, the earlier mixer was not of a straight through type. That earlier mixer included 1st and 2nd elbows (associated with reference numerals 114 and 116 in the patent) in the central recirculation line 54, and included a curved inlet 52 for the dry bulk cement. Because of this design, it was more difficult to flush out and clean the inside of the mixer. Also, it was not possible to see straight through the mixer by breaking open the piping connection at the inlet 52, thus making it more difficult to see inside the mixer to troubleshoot or determine if it was clean when doing maintenance.
Further, the central recirculation line of that earlier mixer was just one additional surface which could be eroded by the abrasive recirculated cement slurry contained within its interior.
Also, the four annular water jets of the earlier mixer had less flow capacity, resulting in higher velocity of liquid streams within the mix chamber to obtain comparable flow rates and thus more erosion of the interior mixer surfaces due to the abrasion caused by the abrasive sand in dirty mix water. Additionally, the earlier mixer employed a somewhat complicated design having multiple passageways, all of which are susceptible to erosion by the dirty mix water. The erosion resulted in more equipment maintenance and shorter equipment life. In an attempt to protect the earlier mixer from erosion, some of the surfaces were either hard coated or constructed of heat treated stainless steel which added to the cost of the equipment.
The present invention addresses each of these problems.
One object of the present invention is to provide a straight through design without any internal centrally located recirculation or water jet pipes that is less inclined to foul and easier to clean than previous designs. Also, this straight design allows the mix chamber of the present invention to be viewed when the connection at the dry powder inlet is broken.
A second object of the present invention is to eliminate the need for a central recirculation line by having more complete coverage in the mixing chamber by employing more annular jets.
An additional object of the present invention is to provide a mixer that employs recirculation jets located upstream of its water jets
A further object of the present mixer is to increase the number and capacity of the annular water flow openings thereby allowing greater water flows with less velocity. The path of recirculation and water flows is such that they do not directly impact the mixer sides and they cause less erosion to the mixer surface than with previous designs. Another object of the present invention is to provide a high performance mixer that has less internal erosion.
A further object of the present invention is to provide a mixer that can be manufactured with lesser expensive materials to thereby reduce the manufacturing cost of the mixer.
A further object of the present invention is to provide a mixer that is less complex in design and therefore reducing manufacturing cost and simplifying maintenance.
Still a further object of the present invention is to provide a mixer that, due to the reduced erosion, will have a longer life and required less maintenance than previous designs. Also disassembly and repair is much simpler with this design.
Another object of the present invention is to provide a smaller, more compact and lighter weight cement mixer.
An additional object of the present invention is to provide a five jet design which allows for more recirculation jets and more water jets than previous designs, resulting in more thorough mixing and better wetting of the cement powder.
An additional object is to have the recirculation jets extending into the dry bulk chamber so as to form a star shape in the bulk inlet chamber which serves to help break up or disperse the incoming dry powder.
These and other objects will become more apparent upon further review of the referenced drawings, detailed description, and claims submitted herewith.